Posted: Fri Mar 09, 2007 9:20 am Post subject:
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Hi Ghozze,
Below is an extract from a useful article on avian genetics. The full article can be read at http://www.oldworldaviaries.com/text/styles/genetics.html
Please note that I had used the expressions "X" and "Y" in my earlier post to avoid confusion as these were the terms used in the extract from "Canary Tales" that I had quoted. The proper terms are “Z” and “W” which refer to the chromosomes of birds instead of “X” and “Y” which refer to those of mammals.
As you know, genetics is complex and even the experts do not fully understand it. What I tried to do in my earlier write-up was to provide very basic information that the beginning breeder might find useful.
You will note that the author of the article is against inbreeding. Without some degree of inbreeding or line breeding, it is impossible to fix the characteristics that we desire. Each breeder will need to decide for himself, the extent to which he will or can go with his inbreeding or line-breeding.
A brief review of avian genetics by Darrel K. Styles, DVM
Quote:
…….. Without getting overly complicated and boring, let's start with the basics. Birds have a mother and a father, just as we all do, and as a result, inherit characteristics of both. The instructions to produce these characteristics are encoded into the DNA of the bird. Each characteristic, such as feather color, is determined by one or more genes, ……….
………
Each chromosome carries thousands or hundreds of thousands of genes, all uniquely encoded by DNA. The presence of genes makes up the "genotype" of an animal. The expression of genes makes up the "phenotype." For example, if a bird has one gene for brown eyes (a dominant trait) and one for red eyes (a recessive trait), then the genotype is brown/red, but the phenotype is brown because brown is dominant over red.
Now let's discuss sex chromosomes. We are all familiar with the concept of genetic sexing. And, many of us know that in humans XY is male and XX is female. These chromosomes carry most of the genes that determine our phenotypic sex. The XY combination is called "heterozygous" meaning different genes, and the XX combination is called "homozygous" meaning the same genes.
Birds are different in that their male and female sex-chromosome roles are reversed from mammals, meaning that the female is heterozygous and the male is homozygous. Also, in birds we use Z and W instead of X and Y. (These letters refer to the general shapes of the chromosomes.) So, a male bird is ZZ, and a female bird is ZW. This leads us to the topic of sex-linked traits.
A sex-linked trait is carried on one of the sex chromosomes, Z or W but usually Z. ………. [Note: As I mentioned in my earlier post, the female will carry the Z chromosome of her father and if we want to propagate the father's genes, the use of the female offspring will more likely enable us to achieve our aim than the use of the male offspring. This is especially so with the first generation progeny.]
……………. The secret of understanding genetics is keeping good records and comparing the results of crossings. In this way you can determine what the actual genotype of the parents is and enhance your chances of predicting the outcomes.
Often, the goal of studying avian genetics is to help in the propagation of valuable mutations. This is most often accomplished by inbreeding. But remember, if you inbreed (cross closely related individuals), you will not only concentrate the desirable genes, such as the lutino cockatiel gene, but also the bad genes, such as bald spots behind the crest. The bald spots appear to be "linked" to the lutino genes and are passed along with them. Also, inbreeding weakens the line. …….
Finally, there are no clear-cut rules on how to proceed with crossings. Experience and time are the best teachers along with your own avicultural intuition. My rule is to avoid inbreeding at all costs unless you are trying to concentrate a specific desirable trait, then proceed with caution.
Showing posts with label Genetics. Show all posts
Showing posts with label Genetics. Show all posts
Wednesday, July 16, 2008
Song Inheritance
Posted: Mon Mar 05, 2007 12:37 pm Post subject: Shama Song Inheritance
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There has been some discussion in this forum on whether the shama’s song ability is inherited or it can be acquired by suitable training. One of the books that has assisted me a great deal in breeding and maintaining my shamas, is not a book on shamas or even of soft-bills but on canaries. While Linda Hogan’s “Canary Tales” is about Roller Canaries, there is much in the book that is applicable to other species. Below is an extract on the song inheritance of canaries which I have applied in my breeding program. By applying, and continuing to apply, Linda’s methods, I hope to eventually breed a super strain of shamas that is more desirable than anything in the wild. For breeders who would like to consider what is required to produce good songsters, I quote below from Linda's book:
How well a bird sings depends on its inheritance. It is estimated that 75% of the birds singing ability is inherited, while 25% of the singing ability is due to training. Since song is inherited as a sex-linked characteristic, to improve the song we must be able to identify the genetic contributions of both the cock and the hen. Sex-linked characteristics are carried on the x chromosome. The song the bird sings is dependent upon the genetic makeup of the two x chromosomes inherited one each from the father and mother. The female canary has one x chromosome and one y chromosome. Her x chromosome was inherited from the father and the y chromosome from her mother. Each male offspring of the hen will inherit the x chromosome she inherited from her father. The cock, in contrast, has 2 x chromosomes, one he inherited from his father and one he inherited from his mother. Male or female offspring have an equal opportunity of inheriting either the x chromosome of his father or the x chromosome of his mother. …… Even though the offspring have the same parents different song patterns are expected because of the combination of x chromosomes inherited from the mother and the father.
The practice of line breeding is one way to improve your bird’s song. A “good” singer can be selected and bred back to its mother. …. When we breed the son back to the mother we increase the mother’s contribution in half of the males as well as reproducing the mothers x song type in half of the females. By evaluating the sons we get a good idea of what the female is contributing to the male offspring’s song.
To get a closer look at both of the father’s x chromosomes we [breed] him back to several daughters and compare the sons’ song…..
Once the appealing combinations are identified, further line crossing can be made to improve the beautiful song. Utilizing half brother/sister combinations, weave a pattern that balances a cock who is strong in bass with a hen whose father was strong in hollow roll and vice versa.
When purchasing breeding stock buy from one breeder who is consistently winning on the show bench. Avoid the temptation to buy unrelated birds from different breeders. Always breed within a strain. When an outcross is necessary return to the same breeder. Only when a suitable outcross is not available, is it necessary to buy an unrelated bird. This unrelated bird should be pure and from a compatible strain. Do not breed males from this pairing because they will not breed true. Rather keep the daughters and breed them back to your original line. Many breeding disappointments can be avoided by always making sure that the breeding male is your pure strain. Outcross males may perform very well on the show bench, but only disappointing results happen when you breed them!
Posted: Thu Mar 08, 2007 12:30 pm Post subject:
--------------------------------------------------------------------------------
Pak David
This one just a correction to Lindas's book. Maybe I am wrong, but I feel I will not wrong because it was a valid knowledge.
She said..."female has one x chromosome and one y chromosome... etc."
In my memory in genetics (Mendel's Law of heredity)... it is a male who has XY genotype and female has XX genotype. So if one male breed to a female, the zygotes bring their parents characteristics (good and bad -dominant (visible) and recessive (not visible) in their chromosome. There are many chromosomes which responsible to bring each of those characteristics.
Example :
female could be xX, XX, or xx let say X = gen for long tail
x = gen short tail
male could be XY X = gen for long tail
Note : characteristic is linked in x chromosomes so Y just indentification for male.
So if we breed a long tailed female, she must has genotype xX or XX but will not xx. (other characteristic will linked in other chromosome; for example human has 46??? type of chromosomes? (if I am not wrong?)
Possibility of their offsprings from xX female are :
X vs X -----> XX born new female like mother (50 %) long tailed
x vs Y -----> xY born new male with short tail (50 %)
Possibility of their offsprings from XX female are :
X vs X ------> XX born new female like mother too
X vs Y ------> XY born new male like father
The same matrics can be used to predict a particular characteristic genetically.
This is just my opinion as comparison... thanks
Regards
Ghozze
Posted: Thu Mar 08, 2007 2:30 pm Post subject: Gene inheritance
--------------------------------------------------------------------------------
Hi Ghozze,
The sex of a mammal is determined by the nature of the sex chromosomes that it has. In mammals the male will have an X chromosome and a Y chromosome (XY) while the female will have two X chromosomes (XX). The opposite is true in birds where the males have XX chromosome and the females XY.
The extract that I placed on the Forum sets out only the very basic principles of gene inheritance with regard to song in birds and possibly other characteristics associated with it, such as display and aggressiveness. It shows that in the planned breeding of birds, the role of the female is likely to be more important than the male to obtain the traits of song that we want. Let me clarify.
Every bird has 2 chromosomes that determine its sex – one that it inherits from its father and one that it inherits from its mother. A male will have two X chromosomes while the female will have an X chromosome and a Y chromosome.
It is the mother bird which determines the sex of the chick. The father cannot determine the sex of the chick as, being male, both its sex chromosomes are X. Consequently, it will always pass an X chromosome to the egg upon fertilization. The female on the other hand, has an X chromosome and a Y chromosome and the chick’s sex will be determined by which of these is in the egg. If the egg has an X chromosome from the mother, the chick that hatches will be male as the egg will invariably receive an X chromosome from the father upon fertilization. If the egg contains a Y chromosome, the chick will be female as the Y chromosome will combine with the X chromosome from the father to produce a female.
From the above it will be seen that the X chromosome that the mother passes to its chick will always have been inherited from her father. Consequently, if we later breed this first generation female chick (F1), we know that the X chromosome that it passes to its egg will have been derived from her father. On the other hand, the first generation male (F1) will have two X chromosomes, one that it received from its father and one that it received from its mother that she inherited from her father in the wild that we know nothing about.
For the above reason, if we are just starting to breed shamas and want to propagate the bloodlines of our favourite male, we are more likely to succeed if we breed from the F1 female progeny rather than from the F1 males.
The position is much improved with the 2nd generation offspring (F2). An F2 female that is bred back to the grandfather will result in more of the grandfather’s genes in the offspring (F3). The egg from which the F2 female hatched will have received an X chromosome from the grandfather. The F2 male offspring will also have received the grandfather's X chromosome through its mother and the grandfather's X chromosome directly from him through the mating to its mother. In other words, both the X chromosomes of the F2 male and the X chromosome of the F2 female will be those from the Grandfather.
As an example, let’s say we are just starting to breed shamas and our aim is to breed the best that we can. Through much effort, we have acquired a beautiful long tailed wild-caught male and we mate him to the best wild-caught female that we can get. The male will pass one of his two X chromosomes to the chick (F1) and hopefully, it will be the chromosome that contains the song characteristics that we want in the progeny. The female will pass her X chromosome (that she inherited from her father) to the male offspring (F1) and her Y chromosome to the female offspring (F1).
If we then breed from the F1 male offspring, it will pass to the egg, either the X chromosome that it received from its father (our favourite bird) or the X chromosome from its mother that she inherited from a male shama in the wild that we know nothing about and which may not have the characteristics that we desire. Breeding from the first generation male offspring will therefore result in more uncertainty in the product that we will get. For this reason, it is preferable that we breed only from the F1 female offspring and not the F1 male offspring.
By using only the F1 female and breeding her back to her father or a close relative of her father, both the male and female chicks in the 2nd generation (F2) will have more of the genes of our favourite bird and we can then use the the males and females from the F2 generation in our breeding program.
As you have noted, the results of breeding are variable and very uncertain and a great deal of luck is required if we are to be successful. Knowing the principles of breeding will help to stack the cards more in our favour.
David
--------------------------------------------------------------------------------
There has been some discussion in this forum on whether the shama’s song ability is inherited or it can be acquired by suitable training. One of the books that has assisted me a great deal in breeding and maintaining my shamas, is not a book on shamas or even of soft-bills but on canaries. While Linda Hogan’s “Canary Tales” is about Roller Canaries, there is much in the book that is applicable to other species. Below is an extract on the song inheritance of canaries which I have applied in my breeding program. By applying, and continuing to apply, Linda’s methods, I hope to eventually breed a super strain of shamas that is more desirable than anything in the wild. For breeders who would like to consider what is required to produce good songsters, I quote below from Linda's book:
How well a bird sings depends on its inheritance. It is estimated that 75% of the birds singing ability is inherited, while 25% of the singing ability is due to training. Since song is inherited as a sex-linked characteristic, to improve the song we must be able to identify the genetic contributions of both the cock and the hen. Sex-linked characteristics are carried on the x chromosome. The song the bird sings is dependent upon the genetic makeup of the two x chromosomes inherited one each from the father and mother. The female canary has one x chromosome and one y chromosome. Her x chromosome was inherited from the father and the y chromosome from her mother. Each male offspring of the hen will inherit the x chromosome she inherited from her father. The cock, in contrast, has 2 x chromosomes, one he inherited from his father and one he inherited from his mother. Male or female offspring have an equal opportunity of inheriting either the x chromosome of his father or the x chromosome of his mother. …… Even though the offspring have the same parents different song patterns are expected because of the combination of x chromosomes inherited from the mother and the father.
The practice of line breeding is one way to improve your bird’s song. A “good” singer can be selected and bred back to its mother. …. When we breed the son back to the mother we increase the mother’s contribution in half of the males as well as reproducing the mothers x song type in half of the females. By evaluating the sons we get a good idea of what the female is contributing to the male offspring’s song.
To get a closer look at both of the father’s x chromosomes we [breed] him back to several daughters and compare the sons’ song…..
Once the appealing combinations are identified, further line crossing can be made to improve the beautiful song. Utilizing half brother/sister combinations, weave a pattern that balances a cock who is strong in bass with a hen whose father was strong in hollow roll and vice versa.
When purchasing breeding stock buy from one breeder who is consistently winning on the show bench. Avoid the temptation to buy unrelated birds from different breeders. Always breed within a strain. When an outcross is necessary return to the same breeder. Only when a suitable outcross is not available, is it necessary to buy an unrelated bird. This unrelated bird should be pure and from a compatible strain. Do not breed males from this pairing because they will not breed true. Rather keep the daughters and breed them back to your original line. Many breeding disappointments can be avoided by always making sure that the breeding male is your pure strain. Outcross males may perform very well on the show bench, but only disappointing results happen when you breed them!
Posted: Thu Mar 08, 2007 12:30 pm Post subject:
--------------------------------------------------------------------------------
Pak David
This one just a correction to Lindas's book. Maybe I am wrong, but I feel I will not wrong because it was a valid knowledge.
She said..."female has one x chromosome and one y chromosome... etc."
In my memory in genetics (Mendel's Law of heredity)... it is a male who has XY genotype and female has XX genotype. So if one male breed to a female, the zygotes bring their parents characteristics (good and bad -dominant (visible) and recessive (not visible) in their chromosome. There are many chromosomes which responsible to bring each of those characteristics.
Example :
female could be xX, XX, or xx let say X = gen for long tail
x = gen short tail
male could be XY X = gen for long tail
Note : characteristic is linked in x chromosomes so Y just indentification for male.
So if we breed a long tailed female, she must has genotype xX or XX but will not xx. (other characteristic will linked in other chromosome; for example human has 46??? type of chromosomes? (if I am not wrong?)
Possibility of their offsprings from xX female are :
X vs X -----> XX born new female like mother (50 %) long tailed
x vs Y -----> xY born new male with short tail (50 %)
Possibility of their offsprings from XX female are :
X vs X ------> XX born new female like mother too
X vs Y ------> XY born new male like father
The same matrics can be used to predict a particular characteristic genetically.
This is just my opinion as comparison... thanks
Regards
Ghozze
Posted: Thu Mar 08, 2007 2:30 pm Post subject: Gene inheritance
--------------------------------------------------------------------------------
Hi Ghozze,
The sex of a mammal is determined by the nature of the sex chromosomes that it has. In mammals the male will have an X chromosome and a Y chromosome (XY) while the female will have two X chromosomes (XX). The opposite is true in birds where the males have XX chromosome and the females XY.
The extract that I placed on the Forum sets out only the very basic principles of gene inheritance with regard to song in birds and possibly other characteristics associated with it, such as display and aggressiveness. It shows that in the planned breeding of birds, the role of the female is likely to be more important than the male to obtain the traits of song that we want. Let me clarify.
Every bird has 2 chromosomes that determine its sex – one that it inherits from its father and one that it inherits from its mother. A male will have two X chromosomes while the female will have an X chromosome and a Y chromosome.
It is the mother bird which determines the sex of the chick. The father cannot determine the sex of the chick as, being male, both its sex chromosomes are X. Consequently, it will always pass an X chromosome to the egg upon fertilization. The female on the other hand, has an X chromosome and a Y chromosome and the chick’s sex will be determined by which of these is in the egg. If the egg has an X chromosome from the mother, the chick that hatches will be male as the egg will invariably receive an X chromosome from the father upon fertilization. If the egg contains a Y chromosome, the chick will be female as the Y chromosome will combine with the X chromosome from the father to produce a female.
From the above it will be seen that the X chromosome that the mother passes to its chick will always have been inherited from her father. Consequently, if we later breed this first generation female chick (F1), we know that the X chromosome that it passes to its egg will have been derived from her father. On the other hand, the first generation male (F1) will have two X chromosomes, one that it received from its father and one that it received from its mother that she inherited from her father in the wild that we know nothing about.
For the above reason, if we are just starting to breed shamas and want to propagate the bloodlines of our favourite male, we are more likely to succeed if we breed from the F1 female progeny rather than from the F1 males.
The position is much improved with the 2nd generation offspring (F2). An F2 female that is bred back to the grandfather will result in more of the grandfather’s genes in the offspring (F3). The egg from which the F2 female hatched will have received an X chromosome from the grandfather. The F2 male offspring will also have received the grandfather's X chromosome through its mother and the grandfather's X chromosome directly from him through the mating to its mother. In other words, both the X chromosomes of the F2 male and the X chromosome of the F2 female will be those from the Grandfather.
As an example, let’s say we are just starting to breed shamas and our aim is to breed the best that we can. Through much effort, we have acquired a beautiful long tailed wild-caught male and we mate him to the best wild-caught female that we can get. The male will pass one of his two X chromosomes to the chick (F1) and hopefully, it will be the chromosome that contains the song characteristics that we want in the progeny. The female will pass her X chromosome (that she inherited from her father) to the male offspring (F1) and her Y chromosome to the female offspring (F1).
If we then breed from the F1 male offspring, it will pass to the egg, either the X chromosome that it received from its father (our favourite bird) or the X chromosome from its mother that she inherited from a male shama in the wild that we know nothing about and which may not have the characteristics that we desire. Breeding from the first generation male offspring will therefore result in more uncertainty in the product that we will get. For this reason, it is preferable that we breed only from the F1 female offspring and not the F1 male offspring.
By using only the F1 female and breeding her back to her father or a close relative of her father, both the male and female chicks in the 2nd generation (F2) will have more of the genes of our favourite bird and we can then use the the males and females from the F2 generation in our breeding program.
As you have noted, the results of breeding are variable and very uncertain and a great deal of luck is required if we are to be successful. Knowing the principles of breeding will help to stack the cards more in our favour.
David
Wednesday, July 9, 2008
Observations on Captive Breeding by Jeffrey Low
First published December 2006
I have to admit that in the past, I had been a little bias as far as captive bred shamas are concerned. I had always thought that they will be lacking in certain character as well as quality in songs and display, that can only be found in the wild ones. Perhaps those captive bred ones I had seen before are not good representatives of what good captive bred shamas are like. My past thinking could have also been partly due to the fact that wild chicks when acquired too young before they had past the stage of storing sounds and songs from the wild, can never measure up to wild chicks that are acquired after this formative period.
My thinking has changed to some extend since seeing David's birds. To breed for the desired physical characteristics, to me is already not an easy thing to do. I had been into selective breeding of other animals and I know for a fact that it takes more than just resources and time to achieve this. To me, what is most admirable is that his birds are not just physically beautiful but they are also not lacking in the other aspects. In his mind, I would think that he has a very clear picture of what the most desirable shama should be like when he started breeding and I respect the man for his dedication towards achieving this.
Comment by David De Souza
Hi Jeff,
I am sure you know this but it may be useful to briefly set out a little of the background on breeding. Everything that man has achieved with regard to animal husbandry has only been because of selective breeding. Our many breeds of dogs have only been brought about because man saw the uses that the dog could be put to and bred for the qualities that were desired. Of course, it takes time to get the type that we want and then to continue breeding until we breed true.
Where man has persisted in his quest he has always succeeded. For instance, nowadays, the wild canary is no longer caught because the domesticated canary sings much better. Through a basic knowledge of genetics, it is possible with much patience to eventually achieve our goal.
When I and others started breeding shamas in 1987, we were just trying to get shamas with long tails. To breed birds with long tails, you look for parents with that characteristic. Long tails is a recessive trait, and it takes time to fix it. Luckily, I acquired Godfather in 2001. He was not only able to pass on his long tails to his progeny and they to their progeny, but many of them also have his character and display.
There is no such thing as the perfect bird but there is satisfaction in trying. We determine the trait that we want and then we selectively mate the birds and their offspring until the characteristic that we want is fixed and we have a bloodline. With regard to trying, take for instance, Godfather’s grandson, Gifted. As you can see from his photos, he has beautiful long tails and a good voice. He is quite a large bird and he does not display much apart from wagging his tails. His son Icon is like him. However, this year, I mated him to an untried female and got a nest of three males and a female who were smaller than him. In Fact, they were all of medium size and exactly the type that I want. They are also much more agile and from the length of their taimong tails I expect they will have long adult tails. I intend to breed Gifted to the same female and to mate his offspring to selected females and so hope eventually to breed exactly the type that I want.
Warm regards,
David
I have to admit that in the past, I had been a little bias as far as captive bred shamas are concerned. I had always thought that they will be lacking in certain character as well as quality in songs and display, that can only be found in the wild ones. Perhaps those captive bred ones I had seen before are not good representatives of what good captive bred shamas are like. My past thinking could have also been partly due to the fact that wild chicks when acquired too young before they had past the stage of storing sounds and songs from the wild, can never measure up to wild chicks that are acquired after this formative period.
My thinking has changed to some extend since seeing David's birds. To breed for the desired physical characteristics, to me is already not an easy thing to do. I had been into selective breeding of other animals and I know for a fact that it takes more than just resources and time to achieve this. To me, what is most admirable is that his birds are not just physically beautiful but they are also not lacking in the other aspects. In his mind, I would think that he has a very clear picture of what the most desirable shama should be like when he started breeding and I respect the man for his dedication towards achieving this.
Comment by David De Souza
Hi Jeff,
I am sure you know this but it may be useful to briefly set out a little of the background on breeding. Everything that man has achieved with regard to animal husbandry has only been because of selective breeding. Our many breeds of dogs have only been brought about because man saw the uses that the dog could be put to and bred for the qualities that were desired. Of course, it takes time to get the type that we want and then to continue breeding until we breed true.
Where man has persisted in his quest he has always succeeded. For instance, nowadays, the wild canary is no longer caught because the domesticated canary sings much better. Through a basic knowledge of genetics, it is possible with much patience to eventually achieve our goal.
When I and others started breeding shamas in 1987, we were just trying to get shamas with long tails. To breed birds with long tails, you look for parents with that characteristic. Long tails is a recessive trait, and it takes time to fix it. Luckily, I acquired Godfather in 2001. He was not only able to pass on his long tails to his progeny and they to their progeny, but many of them also have his character and display.
There is no such thing as the perfect bird but there is satisfaction in trying. We determine the trait that we want and then we selectively mate the birds and their offspring until the characteristic that we want is fixed and we have a bloodline. With regard to trying, take for instance, Godfather’s grandson, Gifted. As you can see from his photos, he has beautiful long tails and a good voice. He is quite a large bird and he does not display much apart from wagging his tails. His son Icon is like him. However, this year, I mated him to an untried female and got a nest of three males and a female who were smaller than him. In Fact, they were all of medium size and exactly the type that I want. They are also much more agile and from the length of their taimong tails I expect they will have long adult tails. I intend to breed Gifted to the same female and to mate his offspring to selected females and so hope eventually to breed exactly the type that I want.
Warm regards,
David
Monday, June 30, 2008
Can Captive-bred Shamas Compete with Wild-caught Shamas?
First posted Oct 2007
We need to assume that the focussed breeder knows what he is doing. Lets say that the knowledgeable shama breeder is trying to breed for specific features. History has shown that in every instance where man has tried over time to produce birds and animals to emphasize certain traits that he desires, he has always succeeded. Ultimately, the wild birds and animals of the species cannot compare meaningfully with the bred birds with regard to the features that man has bred into his birds.
The canary has been captive bred for several hundred years. Is there anyone today who can reasonably claim that the song of the wild canary is preferable to the canary as we know it? The song canary illustrates that we can, over time, produce the type of song that we prefer. Thus the Spanish Timbrado has the bell-like voice that is characteristic of the type; the Roller has the whispering song that can hardly be heard across the room, and the Waterslager has the somewhat wild song that I especially like. BTW, I should mention that I have always gone out of my way to learn from those who had something to teach.
In my younger days, I used to spend weekends and sometimes weekdays at John Yim's home to learn about the shama. When I was interested in breeding canaries some 25 years ago, I took the train to Yorkshire, England, on a winter's day to have tea and discuss breeding Rollers with a champion breeder.
Let's move on to another feature - courage and aggression. Selective breeding has produced the various fighting dogs. The bull dog in times past was bred to fight the bull. It's present short snout was produced so that it could have a better hold on the bull. These dogs would throw themselves on the bull and many would be killed. Then there are the fighting cocks that will continue to try to finish off their opponents even when death is rattling in their throats.
Perhaps we look for speed in our animals. Here again we have examples from the animal and bird world that show us what can be achieved. We have greyhounds, race horses and racing pigeons. For the purposes for which they were bred and trained, I don't think that their wild relations can come anywhere close to them. I could go on and on but I think I have provided sufficient examples of what has been achieved to put beyond doubt that where man has wanted badly enough to breed certain characteristics into his animals and birds he has always succeeded.
Now, what do I want to have in my shamas. Long tails is only one of the features. My concentration is no longer on tails. In other words, it is not my desire to produce birds with longer and longer tails. A tail length of 13" or so is sufficient for what I have in mind. Remember, the bird's physique needs to have balance and proportion and an exaggerated tail length will upset it. Just as important as long soft beautifully curving tails, are song, display, courage, aggression and stamina. I will not go into detail on these features at present but all need to be present in the shama for it to be the bird of my dreams.
If any feature is lacking, my dream shama is the poorer for it. I am applying my mind as to how each of the features can be improved through selective breeding. I am conscious of the benefits and pitfall of line-breeding and inbreeding and take steps to avoid the evils. I still need much time to breed true the features that I desire but I already have with me birds that have much that I am looking for and which encourage me to think that I am on the right track.
We need to assume that the focussed breeder knows what he is doing. Lets say that the knowledgeable shama breeder is trying to breed for specific features. History has shown that in every instance where man has tried over time to produce birds and animals to emphasize certain traits that he desires, he has always succeeded. Ultimately, the wild birds and animals of the species cannot compare meaningfully with the bred birds with regard to the features that man has bred into his birds.
The canary has been captive bred for several hundred years. Is there anyone today who can reasonably claim that the song of the wild canary is preferable to the canary as we know it? The song canary illustrates that we can, over time, produce the type of song that we prefer. Thus the Spanish Timbrado has the bell-like voice that is characteristic of the type; the Roller has the whispering song that can hardly be heard across the room, and the Waterslager has the somewhat wild song that I especially like. BTW, I should mention that I have always gone out of my way to learn from those who had something to teach.
In my younger days, I used to spend weekends and sometimes weekdays at John Yim's home to learn about the shama. When I was interested in breeding canaries some 25 years ago, I took the train to Yorkshire, England, on a winter's day to have tea and discuss breeding Rollers with a champion breeder.
Let's move on to another feature - courage and aggression. Selective breeding has produced the various fighting dogs. The bull dog in times past was bred to fight the bull. It's present short snout was produced so that it could have a better hold on the bull. These dogs would throw themselves on the bull and many would be killed. Then there are the fighting cocks that will continue to try to finish off their opponents even when death is rattling in their throats.
Perhaps we look for speed in our animals. Here again we have examples from the animal and bird world that show us what can be achieved. We have greyhounds, race horses and racing pigeons. For the purposes for which they were bred and trained, I don't think that their wild relations can come anywhere close to them. I could go on and on but I think I have provided sufficient examples of what has been achieved to put beyond doubt that where man has wanted badly enough to breed certain characteristics into his animals and birds he has always succeeded.
Now, what do I want to have in my shamas. Long tails is only one of the features. My concentration is no longer on tails. In other words, it is not my desire to produce birds with longer and longer tails. A tail length of 13" or so is sufficient for what I have in mind. Remember, the bird's physique needs to have balance and proportion and an exaggerated tail length will upset it. Just as important as long soft beautifully curving tails, are song, display, courage, aggression and stamina. I will not go into detail on these features at present but all need to be present in the shama for it to be the bird of my dreams.
If any feature is lacking, my dream shama is the poorer for it. I am applying my mind as to how each of the features can be improved through selective breeding. I am conscious of the benefits and pitfall of line-breeding and inbreeding and take steps to avoid the evils. I still need much time to breed true the features that I desire but I already have with me birds that have much that I am looking for and which encourage me to think that I am on the right track.
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